It is well known that idling, or less than fully loaded, motors waste power. Such is particularly true with AC induction motors, and in U.S. Pat. No. 4,052,648, and in others by the same inventor, there have been disclosed devices which substantially reduce motor losses by controlling the power input to a motor as an inverse function of the detected angle between motor voltage and motor current, or as a direct function of power factor. These inventions have been widely publicized and have provided a major improvement in motor controllers.
One possible problem with power factor type controllers is that in order to provide a sufficiently stable control, the control signal must be subjected to signal conditioning which involves the integration or averaging of the signal. This in turn does involve some delay in motor response, particularly where loads are quite suddenly imposed on a motor.
It is the object of this invention to provide a motor controller which both efficiently supplies power to a motor throughout is operating load range and is capable of rapidly responding to increased motor loading.